MCP Inspector CLI
The official MCP server debugger: web UI, automation CLI and terminal UI in one package
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Extended access
Why this level
- Starts and calls the server under test with all its capabilities
Install
Manual install
npx @modelcontextprotocol/inspectorWeb UI; add --cli for the CLI or --tui for the terminal UI.
Access and checks
How we reviewExtended accessThe tool runs code or makes network calls and only reads external data.
- Starts and calls the server under test with all its capabilities
This is third-party code. Review the repository files before installing.
What it does
Inspector connects to an MCP server and shows its tools, resources and prompts, lets you call them by hand and inspect responses. Web mode gives a visual browser UI, --cli suits scripts and CI, and --tui opens an interactive terminal interface. The CLI has JSON output and exit codes for smoke-testing servers, OAuth ones included. All modes start with a single npx command.
Who it is for. For MCP server developers and anyone checking third-party servers before connecting them to an agent.
Good fit when
- You are writing an MCP server and need to test its tools
- A server fails in a client and you need to find out why
- You need an MCP server smoke test in CI
Not a fit when
- You just want to use a server from an agent, not debug it
- You need load testing rather than manual calls
Example request
Use MCP Inspector in CLI mode to check that my server returns its tool listLimitations
Node.js 22.19 or newer is required. Version 2 changes CLI flags and config format compared with v1; the old line gets security fixes only. The tool does not audit a server's security, it only executes calls.
How to disable. When run via npx there is nothing to uninstall; just stop the process.
FAQ
How do I run the old version?
With npx @modelcontextprotocol/inspector@v1-latest.
Is there a Docker image?
Yes, the repository docs include a container guide.
Discussion
No questions or reviews yet.
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README in short
The README describes the three modes and launching them via npx, the v1 and v2 branch status, and building from source. It shows the repository layout and a table of guides: architecture, test servers, Docker, migration, smoke testing. Contribution rules are in AGENTS.md and procedures are packaged as Claude Code skills. MIT licensed.